linux-kernel - Re: [PATCH net] net/mlx5: report duplex full when speed is known

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Message-ID: <CAHhBTWvcd45s5P-TfKBVzHy00jofbgoWtX+z3Uaj+5ZEBTNLfQ@mail.gmail.com>
Date: Sun, 14 Sep 2025 10:22:35 +0800
From: Li Tian <litian@...hat.com>
To: Andrew Lunn <andrew@...n.ch>
Cc: netdev@...r.kernel.org, linux-hyperv@...r.kernel.org, 
	linux-kernel@...r.kernel.org, Saeed Mahameed <saeedm@...dia.com>, 
	Tariq Toukan <tariqt@...dia.com>, Mark Bloch <mbloch@...dia.com>, Leon Romanovsky <leon@...nel.org>, 
	linux-rdma@...r.kernel.org, Haiyang Zhang <haiyangz@...rosoft.com>
Subject: Re: [PATCH net] net/mlx5: report duplex full when speed is known

On Sat, Sep 13, 2025 at 10:12 PM Andrew Lunn <andrew@...n.ch> wrote:

> I'm confused with your commit message. You say DUPLEX used to be
> reported as Full if the speed is known. How does c268ca6087f55 change
> this?

Because in some circumstances like Azure, mlx5e_port_ptys2speed (now
mlx5_port_ptys2info) does not return a speed. And thus it relies on
data_rate_oper. It reads to me as long as there's no issue acquiring
the speed duplex should be set to full.

> You don't say in the commit message. Why is Half duplex
> important to this fix? I don't see Half anywhere in the code.

It does not return half duplex at all. It would be unknown. I'm just
saying that half duplex shouldn't exist in modern Mellanox 5.

> Also, what sort of problems do you see with duplex unknown?

There were reports of RHEL seeing duplex unknown in ethtool
on Azure Mellanox 5. The intention is to fix this.

Thanks for reviewing.

Li Tian